Ferromagnetic, ceramic body with high quality at high frequency



y 22, 1962 G ZERBES 7 3,036,009

FERROMAGNETIC, CERAMIC BODY WITH HIGH QUALITY AT HIGH FREQUENCY Filed Aug. 11, 1958 INVENTOR. Ea/ EflGES United States Patent .Ofiice 3,036,009 Patented May 22, 1962 3,036,009 FERROMAGNETIC, CERAMIC BODY WITH HIGH QUALITY AT HIGH FREQUENCY Georg Zerbes, Porz-Urbach, Germany, assignor, by

mesne assignments, to Steatit-Magnesia Aktiengesellschaft, Lauf (Pegnitz), Germany, a corporation of Germany, and Indiana General Corporation, Valparaiso, Ind., a corporation of Indiana Filed Aug. 11, 1958, Ser. No. 754,372 1 Claim. (Cl. 252-625) This invention relates to a ferromagnetic ceramic body containing the constituents iron oxide, zinc oxide, and nickel oxide. Such bodies, which have a spinel structure to which is attributed the general formula MeO.Fe O (Me standing for one or more metals) are ferromagnetic and have been known for a long time. been proposed in answer to the growing and ever more demanding requirements of the electrical industry, to add materials to such compositions in order to attain a higher quality value or Q-factor in the bodies especially at high frequencies.

This application is a continuation-in-part of my US. application Serial No. 467,828, now abandoned, filed November 9, 1954.

This invention is based on the discovery that certain small additions of cobalt oxide and manganese oxide favorably modify the properties of nickel-zinc ferrites so that high quality values or Q-factors are obtained in the high frequency range of 200-300 mcs., for example.

The drawing is a triaxial diagram of the three component system ZnO, NiO and Fe O showing in weight percent in quadrangle area ABCD, the group of such compositions to which the invention is applicable.

The corners of the area ABCD represent the follow- 'ing compositions in weight percent.

A is 18% ZnO, 2% NiO and 80% Fe O B is 31.5% ZnO, 2% NiO and 66.5% Fe O C is 2% ZnO, 29.5% NiO and 68.5% Fe O D is 2% ZnO, 18% NiO and 80% Fe O The lower line BC of the quadrangle is just above the 50 mol percent line for Fe O It has been found that at least enough ferric oxide should be present to react with all the bivalent oxides in the composition includ- It has already effective at least a major portion thereof should be in the form of a ferrite.

The addition of cobalt oxide and manganese oxide is effective as a quality improver not only in pure zincnickel ferrites. A valuable feature of the invention relates also to the fact that most impurities as they occur in technical grades of the raw materials (i.e., in zinc oxide, nickel oxide and iron oxide), if they are not present in too great a quantity, do not disturb .the results. Attention is called to the fact that the customary impurity of cobalt oxide in good technical grade nickel oxide is less than the percentage of cobalt oxide which will be established as singularly effective according to this invention. The composition of the invention will tolerate, in part, also larger amounts of other impurities besides cobalt oxide without diminishing quality-improving effects, the elements of adjacent groups and of the 2nd, 3rd and 4th main groups of the periodic table being possible impurities.

In Table l the measured quality values are compared.

Different proportions of additions of cobalt and manganese oxide, or cobalt and manganese compounds which on heating go over to the oxides, naturally change the properties of the manufactured ferromagnetic body. With increasing cobalt content, the Q-factor increases up to a maximum and then again diminishes.

The useful improvement in the quality through the incorporation of cobalt in the ferrite lattice according to the invention is found when between 1 and weight percent of cobalt oxide determined as C00 and with respect to the content of NiO are present. The amount of cobalt oxide based on the total weight of the composition is between 0.1 and 3%, but no less than 1% or no more than 60% based on the content of nickel oxide employed.

With the manganese as with the cobalt oxide, it is small quantities of the order of magnitude of 1 weight percent of the batch, which effects the improvement, yet the manganese can be considerably increased (up to 5% by weight of the composition, for example) without diminishing the effect.

Table 1 shows a series of tested examples and a comparative relationship of properties of the ferrites of the invention with the cobalt and manganese oxide addition.

Table 1 Composition in Weight Q at 1 Megacycle percent Q 1mn With cobalt prove- C00:

manganese ment, NiO ZnO NiO F6203 Without additions, 000 percent addition =().7% of batch,

Mn0=2% of batch The ferrites which are the basis of the invention are prepared and measured as follows: The raw materials with an addition of water and an organic binding agent are ground in a ball mill, the slurry mass is dried, pulverized and then pressed to form a ring. The ring is fired in air at a temperature between 1100 and 1350 C., after cooling the fired ring is wound with 28 turns of 0.3 mm. thick, lacquered copper wire and the quality and inductivity is measured in the radio broadcast frequency range on a commercial Q- and L-measuring apparatus. From the inductivity and the dimensions of the ring the initial permeability -,u. is determined. With 28 turns, not the maximum Q value of the materials but serviceable comparable values are obtained, so that the method of preparation with all batches are substantially similarly considered except for the firing temperature. These have been varied somewhat so that comparable initial permeability values in the range of the maximum Q-value results. In order not to be too voluminous the Quality factor at one megacycle is given.

I claim:

A magnetic core body having a high Q-factor in the high frequency range of up to 300 mcs. comprising a sintered nickel-zinc ferrite prepared by firing at about 1100 C. to about 1350 C. a composition consisting essentially of the NiO, ZnO and ferric oxide components set forth in weight percent within the area ABC-D of the drawing, said composition comprising in addition 1 to 5 weight percent of manganese oxide based on the total weight percent, and 1 60% by weight of cobalt oxide based on the proportion of nickel oxide in the said composition, the amount of cobalt oxide being within 0.1 to 3.0% by weight of the total composition, the pro portion of iron oxide in said batch being at least 50 mol percent of the entire composition.

References Cited in the tile of this patent- UNITED STATES PATENTS 2,656,319 Berge Oct. 20,1953 2,700,023 Albers-Schoenberg Jan. 18, 1955 2,723,239 Harvey Nov. 8, 1955 2,736,708 Crowley et al. Feb. 28, 1956 2,925,388 Harvey Feb. 16, 1960 FOREIGN PATENTS 751,623 Great Britain July 4, 1956 752,659 Great Britain July 11, 1956 OTHER REFERENCES Smiths College Chemistry 6th ed., p. 643, pub. by D. Appleton-Century Co., N.Y., 1946. 

